Salvage pontoon

ABSTRACT

A salvage pontoon characterized by flat suction coupling plates, object attaching arms having explosive driven studs, and a cryogenic gas supply is disclosed. A ballast arrangement is disclosed to permit raising of the object and attached pontoon in controlled increments.

United States Patent 1191 Odum et a1.

[ 1 SALVAGE PONTOON [75] Inventors: William T. ()dum, Panama City; JamesH. Elkins, Lynn Haven;

Thomas M. Coggins, Panama City, all of Fla.

[73] Assignee: The United States of America as represented by theSecretary of the Navy [22] Filed: May 5, 1971 [211 App]. No.1 140,438

52 u.s.c1 ..ll4/53,l14/16.4 51 1m.c1 ..B6 3 c7/08 5s FieldofSearch..114/50,51,53,52, 114/164, 16 E, 16 R; 61/69, 71; 9/8; 294/64 [56]References Cited UNITED STATES PATENTS Sellner et a1. ..1 14/16 EPrimary Examiner-Milton Buchler Assistant Examiner-Gregory W. OConnorAzt0rneyRichard S. Sciascia, Don D. Doty and William T. Skeer ABSTRACT Asalvage pontoon characterized by flat suction coupling'plates, objectattaching arms having explosive driven studs, and a cryogenic gas supplyis disclosed. A ballast arrangement is disclosed to permit raising ofthe object and attached pontoon in controlled increments.

9 Claims, 7 Drawing Figures Patented May 1, 1973 3,730,122

3 Sheets-Sheet 1 WILLIAM T. ODUM JAMES H. ELKINS THOMAS M. COGGINSINVENTORS BY Q ZQZM f 1% Ja /4A ATTORNEY INVENTORS f {11 A WILLIAM T.ODUM JAMES H ELKINS THOMAS M. COGGINS 3 Sheets-Shut 2 I! ////I F F A w:

Ev 6? .ON

Patented May 1, 1973 ATTORNEY Patented May 1, 1973 3 ShutbS'nuc 3 TOPONTOON l2 FIG.6

W'LLIAM T. ooum JAMES H. ELKINS THOMAS M. COGGINS INVENTORS BY ff MSALVAGEPONTOON STATEMENT OF GOVERNMENT INTEREST The invention describedherein may be manufactured and used by or for the Government of theUnited States of America for governmental purposes without the paymentof any royalties thereon or therefor.

CROSS REFERENCE TO RELATED APPLICATIONS This application discloses avariable buoyancy pontoon which is a component part of a deep seasalvage system. Other components of the system include a manned deep seavehicle disclosed in US. Pat. application Ser. No. 132,032, filed Apr.7, 1971, for Salvage Work Vehicle, by the applicants in thisapplication, and an electrical connector disclosed in US Pat. No.3,665,509, filed Mar. 22, 1971, for Underwater Electrical Connector byJames H. Elkins.

FIELD OF THE INVENTION This invention pertains to the field ofoceanographic engineering. More particularly, but not by way oflimitation, the invention pertains to deep sea salvage. In still greaterparticularity, the invention pertains to a pontoon which may be used fordeep sea salvage or in other oceanographic tasks where great weight mustbe lifted from the ocean depths, such as is sometimes required incertain oil well drilling operations on the ocean floor.

As nuclear power plants become more common and payloads of chemicalproducts increase, the risk of ocean pollution by marine accidents growsgreater. Of course, recent design changes in ships having these contentshave reduced the danger to a great extent. Despite these changes in shipdesign, it becomes more urgent that a method and means be available torecover marine wrecks from the ocean floor to avoid massive oceanpollution therefrom. Quite naturally, the economic value of the salvageis also of considerable importance. It is also desirable to recoverwreckage of vessels in which the cause of their sinking is unknown. Thestudy of such wrecks is valuable in the design of new ships in order toprevent similar disasters from recurring.

DESCRIPTION OF THE PRIOR ART The most successful prior art system ofrecovery of massive loads from the ocean depths has employed surfacelifting techniques. In such operations, a surface pontoon is positionedabove the object to be lifted and a lifting cable is attached to theobject to be recovered. The object is then raised to the surface byhauling the cable upwardly.

This operation requires great expenditures of time and money to positionand operate the powerful winches. The system is also weather dependentsince the success of the operation depends upon a calm sea. The load tobe lifted, when attached to the cable, becomes a massive pendulum andgreat care must be taken to avoid attendant mechanical resonances. Suchmechanical resonances could exceed the structural strength of theequipment causing the load to sink again. Such repeated sinkings notonly damage the salvage equipment and cause expensive delays, but

often cause further damage to the salvage object risking pollution andeconomic loss. Loads of 110 tons have been raised in this fashion butare considered to be the limiting size for this type of salvageoperation.

SUMMARY OF THE INVENTION This invention provides a submersible salvagepontoon which is maneuvered into direct contact with the object to belifted by manned deep submergence vehicles. The pontoon is attached tothe object to be lifted by the crew of the manned vehicle or by remotecontrol from the surface. The attachment to the salvage objects is madeby one of several different types of support arms described herein. Whenthe pontoon is attached, it is made positively buoyant by release ofsuitable ballast carried therein and by displacing water therefrom bygas supplied by two large cryogenic dewars carried therein. The rate ofascension of the pontoon is controlled from the surface by a mechanismwhich releases, upon command, lengths of steel cable connecting thepontoon with the ballast.

When the pontoon, with its load attached, has reached a modest depth,lines are made fast to the load and connected to surface barges orpontoons and the salvage operation may continue from the modest depthsin a conventional fashion.

Each pontoon of the invention is capable of lifting 300 tons from l50fathoms, a heretofore unprecedented salvage capability.

With the foregoing description in mind, it is an object of thisinvention to provide an improved salvage pontoon.

It is a further object of this invention to provide an improved methodand means to lift submerged objects from the depths of the ocean to thesurface thereof.

It is another object of this invention to provide a salvage buoy with aself-contained variable buoyancy system.

It is another object of the invention to provide a salvage pontoon whichmay be attached to a variety of submerged loads by remote control.

Another object of this invention is to provide a salvage pontoon with aliquified gas supply therein.

A further object of the present invention is to provide a salvagepontoon with improved lift capabilities.

A still further object of this invention is to provide a salvage pontoonwith interchangeable load attaching supports.

Another object of this invention is to provide a salvage pontoon havingimproved submergence and surfacing apparatus.

Yet another object of this invention is to provide a salvage pontoonwhich is designed to be positioned by deep submergence vehicles.

A further object of this invention is to provide a salvage pontoon witha ballast control system to permit the rate of emergence thereof to becontrolled from the BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is anelevation view of the pontoon of the invention in a hypotheticaloperational environment;

FIG. 2 is an end elevation view of the pontoon of the invention showinga tubular attachment arm and a flexible attachment means;

FIG. 3 is a side elevation view of the pontoon of the invention with thebody portion thereof shown in partial section;

FIG. 4 is a diagrammatic showing of the restraining cable and ballastarrangement according to the invention;

FIG. 5 is a perspective view of the restraining cable attachmentarrangement;

FIG. 6 is a sectional view of a plate type attachment arm taken alonglines 66 of FIG. 3; and

FIG. 7 is a plan view of the mounting plate arrangement used on tubulartype attachment arms.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a load,such as a sunken ship 11, to be raised is shown as resting on the seabottom. A salvage pontoon 12 is attached thereto by suitable arms 13. Adeep submergence salvage work vehicle 14 is attached to each end ofpontoon 12 for positioning thereof relative to ship 12 prior to theattachment of arms 13 thereto. Deep submergence vehicle 14 has anexternal manipulator arm 15 which is used for attaching arms 13 to ship11, for moving conductor 16, and other purposes. When pontoon 12 ispositioned in cooperative relation to ship 11, deep submergence vehicle14 may separate therefrom and maneuver independently.

An electrical conductor 16 is lowered from the sea surface and has aconnector plug 17 secured to the distal end thereof. As will beunderstood by those familiar with salvage operations, plug 17 is graspedby arm 15 and inserted into a receptacle 18, which is mounted on pontoon12. In instances where a plurality of pontoons 12 are required, a singleconductor 16 may be lowered from the surface with a junction box, notshown, on the distal end thereof, in place of connector 17. Furtherconductors emanating from the junction box with connectors 17 thereonare placed in receptacles 18 on the individual ones of the plurality ofpontoons 12.

Attachment of the deep submergence salvage work vehicle 14, hereaftertermed salvage vehicle, to salvage pontoon 12 is accomplished by meansof a suitable vacuum or hydrostatic coupler 19. Couplers l9 cooperatewith flat portions, to be more completely described herein, on each endof salvage pontoon 12 in such a manner as to attach salvage vehicles 14thereto. If desired, salvage vehicles 14 may be interconnected so thatcontrol thereof may be exercised from a single vehicle. This controlinterconnection may be accomplished by a fixed wire communication linkwithin salvage pontoon 12, or, if desired, by an acoustic wave, i.e.,sonar-like, communication link through the water. Both of thesearrangements may be incorporated in each salvage vehicle, one serving asa back-up system for the other, if desired. The exact nature andfunctioning of the control system has no direct bearing to the presentinvention and, since prior art systems capable of providing thecommunication link are well known, the selection of a suitable system isleft to the choice of the skilled worker making and using the invention.

Referring now to FIG. 2, an end elevation of pontoon 12, it may be seenthat pontoon 12 comprises a box-like base portion 21 and a cylindricaltank-like buoyant portion 22. Suitable supports 23, spaced atpredetermined intervals, join base portion 21 and buoyant portion 22.The number and location of supports 23 are, of course, depend upon thematerial from which they are made and the expected loads to be bornethereby. It should be noted that the illustrated configuration is but anexemplary construction and other arrangements are possible. For example,base portion 21 may extend upwards to join and partially enclosebuoyancy portion 22 so as to incorporate supports 23 as integralportions thereof. These constructional details are well understoodparameters of design to persons familiar with the fields of navalarchitecture and, quite naturally, may be varied to suit the individualcircumstances of the particular requirements. For purposes ofexplanation, it need only be noted that the construction serves torigidly unite the component parts of pontoon 12 into a rigid assemblycapable of withstanding the loads placed thereon.

On suitable bulk heads, to be more completely described, located at eachend of cylindrical buoyant portion 22, coupling plates 20 are located.Coupling plates 20 serve as attachment points for vacuum couplers 19 andmay simply be flat steel plates, if desired. However, since the vacuumseal is the means by which pontoons 12 are moved by salvage vehicles 14,coupling plates 20 may be modified to promote cooperation with theirmating parts. One type of modification includes a coating of the surfaceof coupling plate 20 with a plastic or synthetic rubber compound topromote a watertight seal therewith by gasket means on vacuum coupler19. In place of coatings, or in addition thereto, the face of plate 20may be figured to promote a watertight seal. Such figuring is wellunderstood in the vacuum attaching and vacuum chuck arts. The selectionas between coatings, figurings and combinations of the two is regardedas a matter of design choice.

Along the center of the upper surface of buoyant portion 22, wherereceptacle 18 is located, a plurality of suitable hatches 24 areinstalled. Hatches 24 permit crew members to enter the interior of thebuoyant portion 21 for service thereof. Of course, in operation pontoon14 is unmanned and the hatches are secured. Since entry into the buoyantportion 21 is infrequent, hatches 24 may be secured with threadedfasteners or other semi-permanent fastening means.

Receptacle 18 may be any multiconductor electrical connection meansconstructed for electrical connection in underwater environments. Forexample, the connector described in the aforementioned US. Pat.

No. 3,665,509 for Underwater Electrical Connector,

filed Mar. 22, 1971, by James H. Elkins, one of the inventors of theincident invention, was especially designed for this application.However, the successful operation of pontoon 12 does not depend on anyparticular electrical connector construction and, accordingly, nospecific construction thereof is shown herein.

Buoyant portion 22 contains, in suitable interior compartment means,suitable, large-volume, cryogenic Dewar flask means 25. Suitable supportmeans 26 provide secure mounting for Dewar flash means 25. A morecomplete explanation of this portion of the invention will be providedin connection with the description of FIG. 3, where the details of thecryogenic Dewars are more clearly shown.

Base portion 21 houses, along with other components, the ballastcomponents of pontoon 12. A weighted hatch 26 has an eye bolt 27extending therethrough. A suitable ballast chain 28 is secured to eyebolt 27 and disposed within a ballast compartment 30 within base portion21. As will be more completely described presently, the ejection ofhatch 26 along the direction shown by arrow 29 drags ballast chain 28thereafter to cause the lightening of pontoon 14. Although a pluralityof hatches 26 are provided, only one is shown as being deployed forpurposes of illustration. In operation all are deployed simultaneously.

Ballast chain 28 is of any suitable construction to provide thenecessary weight, so as to obtain the desired change of buoyancy whenejected. In a developmental embodiment of the invention standard anchorchain has proven satisfactory. The type of chain employed was twelvecentimeter chain weighing 7,600 Kg per 25 meter shot. If heavier chainis required, it may be especially fashioned for this purpose and maycomprise lead clad steel links, for example. Of course, if lesserweights are specified, other stock chains may be employed. Theterminology ballast chain as used herein may refer to any suitableconfiguration of ballast weights and should not be construed as limitedto the linked chain form disclosed herein. However, the restrainingcontrol means, to be described presently, limits the ballast to someunitary construction that may be made fast to a line or cable.

The attachment arms, shown generally at 13 in FIG. 1, are also carriedby base portion 21. Attachment arms 13 are of two general types, rigidand flexible. Each type of arm is mounted on a pair of outwardlyextending mounting bosses 31. A plurality of pairs of bosses 31 extendalong each side of base portion 21 to permit the number of arms to beselected in accordance with the particular circumstances. For purposesof simplicity of illustration, arms are shown as being attached to onlyone side of base portion 21. In actuality, of course, both sides of baseportion 21 have arms attached thereto.

Likewise, for purposes of explanation, two types of arms are shown inFIG. 2. It should be understood, in actual practice, only a single typeof arm need be used. Some situations, however, may require the use ofarms of different types, as illustrated.

One type of arm is formed of a belted chain 32. Belted chain 32 offersthe advantage of conforming to a variety of different load shapes. Also,belted chain 32 permits fastening pontoon 14 to loads, such as ship 11,in such a fashion as to lift the load in a different orientation than itis found in. Thus, belted chains 32 may be attached to the port andstarboard sides of the deck of a wreck lying on its side so as to liftit in an upright fashion.

FIG. 2 also illustrates a tubular arm 33 mounted on base portion 21.Although shown as straight, tubular arm 33 may be formed so as to fitand captively embrace irregular shapes such as specific hull shapes. Atthe outboard end of arm 33, a mounting plate 34 is hingedly attached soas to be movable to rest in surface contact with the object to be liftedat a suitable mounting point thereon. Mounting plate 34 will be morecompletely described herein.

Rather than depending vertically downwardly, as in the case of beltedchain 32, tubular arm 33 may be held outwardly from pontoon 12 bysuitable support means, such as a chain 35, extending between eyes 36 onthe outer end of tubular arm 33 and on buoyancy portion 22. Provisionsmay also be provided, if desired, for adjusting the length of thesupport means and, thereby, the position of tubular arms 33. Such alength adjustment may be provided for chain 35 by a turnbuckle 37.Means, not shown, may also be provided to sever or otherwise part chain35 to cause arms 33 to drop from their outwardly supported position to adownwardly extending position. This arm repositioning operation may beaccomplished when salvage pontoon 14 is in the desired position withrespect to the object to be lifted.

Referring now to FIG. 3, a side elevation of salvage pontoon 12 with aportion thereof broken away for illustration purposes. However, in placeof tubular arms 33, plate arms 38 are shown mounted on either end ofbase portion 21 in bosses 31. As previously indicated, bosses 31 are ofa standard spacing to accept a variety of attaching means to connectpontoon 14 to the load to be raised, such as ship 1 1. In this regard,the varieties of arms shown and described herein should be regarded asonly exemplary embodiments. As the number of salvage pontoons 12increase and they become more commonly available, it is envisioned shipsplying the world waterways will carry arms or other fittings to bereceived and held by standard arms or attached directly to bosses 31.

It should also be apparent that bosses 31 themselves, are subject tomodification. Of course, other attachment means may be installed on baseportion 21 to receive the standard attachment arms. Accordingly, asexperience is gained in the use of the pontoon of the invention, skilledworkers may make desired modifications to the invention withoutdeparting from the scope thereof.

Buoyant portion 22 has a cylindrical hull portion 39 closed at each endwith end bulkheads 41. As previously noted, coupling plates 20 arelocated on bulkheads 41. As shown, salvage pontoon 12 is symmetrical andboth end bulkheads 41 are of the same shape. However, if desired, theycould be configured to provide a more hydrodynamically shaped bow at oneend to enhance surface towing of pontoon 12 so as to promote surfacetransport thereof to the site of the salvage as well as hasten thedeployment thereof.

In either construction, symmetrical or unsymmetrical, bulkheads 41cooperate with hull portion 39 to form a stressed enclosure for thecryogenic gas supplies and other components to be kept dry and atregulated pressures. Hull portion 39 is made of sheet steel withreinforcement provided by suitable ribs 42 spaced at predeterminedintervals therealong. Ribs 42 are of 1 section steel although otherstructural shapes may be used, if desired.

Two interior bulkheads 44, one shown, divide the interior of buoyantportion into three compartments.

Aside from their portioning function, bulkheads 44 add compressionalstrength and torsional rigidity to the structure of buoyant portion 21.Bulkheads 44 are substantially the same as the exterior and bulkheads 41with the obvious exception that they have no coupling plate installedthereon. Bulkheads 44 are spaced in such a predetermined fashion thatthe end compartments defined thereby are of smaller volume than thecenter compartment located therebetween.

A cryogenic Dewar is located in each of the end compartments. Althoughthere are other components of the salvage pontoon system locatedtherein, the size of Dewar 25 primarily determines the placement ofbulkheads 44 and, therefore, the relative sizes of the compartments.Cryogenic Dewar 25 is held in place against the forces resulting fromthe movement of pontoon 12 by a suitable support means 45. Dewar 25 andits support means 45 are conventional state-of-the-art components whichare well known in the cryogenic engineering arts. Since several typesthereof are available, the choice between them is left to the proficientartisan.

Each Dewar 25 is of sufficient size to exhaust the central compartmentof water. The two Dewars 25 have, therefore, the combined capacity tomake two salvage lifts before requiring replenishment. Dewars of suchlarge capacity require pressure regulation to perform at deep oceandepths. Pressure regulation is provided by suitable pressure regulators46 which, like Dewar 25, is of conventional state-of-the-artconstruction. The boil-off gas is vented to the outside by regulator 46by means of a conduit 47.

The center compartment of buoyant portion 22, located between bulkheads44, comprises the variable buoyancy portion of pontoon 12. Water, whichfills the compartment during periods of negative buoyancy and partiallyfills the compartment during periods of neutral or controlled buoyancy,is pressure equalized by means of a standpipe 48. As may be seen in FIG.3, standpipe 48 communicates between the interior of the centralcompartment and the outside ambient water.

Standpipe 48 is of an inverted U shape having open ends. The interioropening thereof is near the deck, or lower surface, of the centralcompartment. The interior opening is in one end of standpipe 48. Theother end thereof is somewhat longer and penetrates the cylindrical hullportion 39 to open on the exterior of buoyant portion 39. Standpipe 48is mounted by means of triangular braces 49 which, in addition to theirsupporting function, brace standpipe against flexure caused by movementof water at high pressures therethrough.

The transfer of gas from Dewar 25 to the central compartment isinitiated by response to an electrical command signal from the surfacetransmitted via electrical conductor 16, electrical connector 17(FIG. 1) and receptacle 18. The internal wiring of pontoon 12 is notshown since it is not necessary for the understanding of the inventionand since, even though complex and extensive, such wiring systems arewell understood and within the skill of one versed in the marineengineering arts. The draining of the liquified gas from Dewar 25 iscontrolled by cryogenic control valve apparatus 51.

Rather than supply gas directly to the buoyancy compartment, valve 51routes the gas, via conduit 52, to a heat exchanger 53. As will be wellunderstood by those familiar with liquified gases, the change of statefrom a liquid to a gas is accompanied by a thermal exchange. If anattempt is made to effect the exchange directly there would be dangerthat the water surrounding the discharge end of the conduit would freezeto create a blockage thereat. Such blockage, coupled with the rapid riseof pressure, might result in explosive forces being generated within thesystem. The presence of heat exchanger 53 in the system lessens thispossibility. Heat exchanger 53 is located within base portion 21 and isin thermal contact therewith and with the surrounding water. The gaseousoutput from heat exchanger 53 is transferred to the interior of buoyantportion 22 by means of conduit 54 connected therebetween. Of course,some thermal transfer occurs as the gas passes through conduits 52 and54. The temperature of the gas is raised until it enters the centralcompartment, where its temperature is above the freezing point of seawater.

The gas entering buoyant portion 22 displaces the water therein throughstandpipe 48 in the well understood fashion common within the submarineengineering discipline. The ejection of the water therefrom and itsreplacement with gas from Dewar 25, of course, results in a change ofbuoyancy for pontoon 12.

Before pontoon 12 is attached to the object to be raised, its buoyancyis controlled to closely approximate neutral buoyancy by control valve51. After pontoon 12 is attached, the ballast is jettisoned and valve 51controls the buoyancy to provide positive buoyancy so as to raise theobject to the surface. Control valve 51 is actuated from the surface,via the previously described control link, to accomplish the desiredchanges in degree of buoyancy regulation.

As previously described, ballast chain 28 is jettisoned by releasinghatch 26 to which it is attached by eye bolt 27. Hatch 26 is held inplace in base portion 21 by means of latch bolts 55 which engagecooperating holes 56 in the margin thereof. Latch bolts 57 areexplosively severed upon receipt of electrical .command signals from thesurface, as obviously described. As the ballast chain 58 pays out, thebuoyancy of pontoon 12 and its attached load alters to become positiveso as to start to ascend.

As is well understood, an uncontrolled ascent is not desired. To providea control for the rate at which pontoon 12 surfaces ballast chain 28 isconnected to suitable restraining cable means 57, see FIG. 4, bysuitable attaching tackle 58. Of course, restraining cable 57 isattached to base portion 21 of salvage pontoon l2 and is of sufficientlength to reach the surface, or to the height from the bottom to whichit is desired to lift the salvaged object. However, rather than beingpayed out continuously or at one time, restraining cable 57 is payed outin predetermined lengths so as to permit pontoon 12 and its attachedload to be raised in controlled increments. To accomplish this end, saidpredetermined lengths of restraining cable 57 are wound into a pluralityof loops 59. Each loop 59 is bridged by a short length of cable 61 withan explosive cutter 62 positioned in cooperative relation thereto.

Cable 61 provides strain isolation for its associated loop 59. Firingeach cutter 62 severs short cable 61 and thereby permits the particularloop 59 associated therewith to be payed out.

Referring to FIG. 5, restraining cable 57 has the loops 59 placed insidea frangible tube 63. This constructional convenience permits the storageof a considerable number of loops 59 without entanglement. Loops 59 areadhesively secured to the inner surface and explosive cutters 62 arepositioned along the outer surface and extend the walls of tube 63. Thebuoyancy force of pontoon l2 extracts cable 57 pulling it free of tube63. Tube 63 may break away as cable 57 is withdrawn therefrom. Insteadof a single tube with circular coils 59, a double tube arrangement withfigureeight shaped coils, not shown, may be used, if desired. Such analternate arrangement requires a smaller tube length for a given lengthof restraining cable 57. Tubes 63 are located within base portion 21 andcutters 62 are electrically fired in sequence on command from thesurface.

Referring to FIG. 6, a sectional view of plate arm 38 taken along line6-6 of FIG. 3, one will see that the structure is built on a T sectionbeam 64. A plurality of threaded holes in the flange, or base plateportion, of beam 64 accept explosive driven stud assemblies 65 therein.Explosive driven stud assemblies 65 are conventional state-of-the-artunits. Stud assemblies 65 are fired electrically from the surface viathe aforedescribed command link. Conductors 66 on arm 38 complete thecircuit to the individual stud assemblies. Gaskets 67 are located alongthe object engaging surface of arm 38 form watertight contact with theobject to be lifted when arm 38 is resting thereon. Gaskets 67 togetherwith arm 38 form a vacuum gripping surface with the object to be liftedin the same manner as vehicle 14 attaches pontoon 12 thereto. A sourceof vacuum connected thereto by conduit means, not shown, causes arm 38to be drawn into contact with the object to be lifted. This contactenhances the penetration and effectiveness of explosive driven studs 65.

Referring to FIG. 7, the distal end of tubular arm 33, as illustrated inFIG. 2, is shown. As may be seen, mounting plate 34 is attached to arm33 by means of a hinge 68. Like plate arm 38, previously described,mounting plate 34 has a plurality of explosive driven studs 65 mountedthereon. To increase the area of attachment ears 69 may extend outwardlyfrom plate 34 with studs 65 mounted thereon.

Chain belt arms 32 may also carry mounting plates 31 at the distal endsthereof.

MODE OF OPERATION Having described the construction ofa preferredembodiment of the invention, the manner of employment of the device toaccomplish the objects of invention will now be set forth.

Salvage pontoon 12 is first transported to the salvage cite. This may beaccomplished either with surface towing techniques or as deck cargo on asuitable salvage vessel or barge. When at the salvage cite and in thewater, salvage work vehicles 14 take salvage pontoon 12 in tow andtransport it to the wreck, or other object, to be raised thereby.Attachment of work vehicle 14 to pontoon 12 is made by a vacuum couplerattached to coupling plate 26. During this transportation time, valvemechanism 51 regulates the buoyancy of pontoon 12 to assure that it isneutrally buoyant.

When pontoon 12 is in place with respect to the wreck, work vehicle 14detaches itself therefrom and positions the lifting arms in place withrespect to the wreck. The precise operations performed depend in largemeasure on the particular type of arm that is fitted on salvage pontoon12.

If the belted chain arms 32 are fitted, the crew in salvage work vehicle14 move the end thereof into cooperative arrangement with ship 11, orother object to be raised. In some instances, salvage pontoon 12 may beplaced alongside ship 11 and connections of belted chain arms madethereto in such a manner that ship 11 is raised in a different attitudethan it occupies on the bottom. The particular manipulative steps dependupon the precise nature of the fastenings on chain belt arms 33. Ifmechanical fittings are employed, the connections are made by the use ofmanipulator 15. If explosive driven studs are employed, the crew of workvehicle 14 place the terminating pad on which studs 65 are mounted inthe desired position to which attachment is to be made. This mountingpad, not illustrated in the drawings, may be the same as mounting plate34 used on tubular arm 33.

If the inflexible tubular arms 33 are used on salvage pontoon 12, thedegree of manipulation by the crew of work vehicle is correspondinglyless. In such instances, the work vehicle crew releases arms 33 from thesupporting chains 35 to cause them to come to rest on ship 11. Plates 34are hinged into operating position by use of manipulator 15 when tubulararms 33 are in place.

A similar positioning procedure is employed if plate arms 38 are mountedon salvage pontoon 12. When arms 38 are equipped with the vacuumattachment means, the crew of work vehicle 14 make the necessary vacuumconnections thereto to draw arms 38 tightly into contact with ship 11prior to the detonation of explosive driven studs 65.

As previously noted, the rigid type arms may be shaped to conform to thedesired object shape which is to be raised to the surface. For example,if a small diameter submarine vehicle is to be raised the arms may beformed to encircle the load. If, however, the object to be raised is ofa large diameter the arms may be curved to conform to the surface so asto thereby promote contact therewith without encircling the load. Thelinear arms used as exemplary constructions herein may be regarded asbeing shaped to conform to barges or the flat plate sections of largeocean going ships.

When pontoon 12 is in place and attached to ship 1 1, electricalconductor 16 is lowered from the surface and connector 17, attachedthereto, is placed in receptacle 18. In instances where plural pontoons12 are placed on ship 11, conductor 16 may terminate in a junction boxand a plurality of short cables each with a connector 17 on the end ofeach thereof. When plug 17 is in receptacle 18, command of salvagepontoon 12 is exercised from the surface.

When the particular arms in use are in position and the command link tothe surface is established, explosive studs 65 are fired to firmlyattach pontoon 12 to ship 11. Ballast is then jettisoned by detonatinglatch bolts 55 which cause hatches 26 to be expelled dragging ballastchain 28 therebehind. Work vehicles 14 may assist in this operation toassure that hatches 26 and the ballast chain attached thereto are freeof ship 11 as well as pontoon 12. In some embodiments it may bedesirable to route ballast chains 28 through tubular arms 33 withhatches 26 at the outboard ends thereof.

When pontoon 12 is unburdened of ballast, valve 51 regulates thebuoyancy of pontoon l2 and attached ship 11 to be positive. Havingpositive buoyancy, pontoon l2 rises to the level permitted byrestraining cable 57. Ship 11, being attached thereto, rises withpontoon 12. When at the height permitted by restraining cable 57 valve51 readjusts the buoyancy of pontoon 12. If

plural pontoons are used, the trim or attitude of the ship 11 andpontoon 12 combination is adjusted at this time by regulating therelative buoyancy of the several pontoons 11. I

When pontoon l2 and ship 11 have been stabilized in the desiredattitude, an explosive cutter 61 is detonated to release a loop 59 ofrestraining cable 57 to allow pontoon 12 together with ship 11 to riseanother predetermined increment. This process is repeated until pontoon12 has raised ship 11 to the surface or other desired working level.

Obviously, other embodiments and modifications of the subject inventionwill readily come to the mind of one skilled in the art having thebenefit of the teachings presented in i the foregoing description andthe drawings. It is, therefore, to be understood that this invention isnot to be limited thereto and that said modifications and embodimentsare intended to be included within the scope of the appended claims.

What is claimed is:

l. A salvage pontoon for use in recovering a large object from a greatocean depth comprising in combination:

buoyant chamber means for providing regulatable buoyancy for saidpontoon;

base portion means attached to said buoyant chamber means for providingmutual support therebetween;

object engaging arm means attached to said base portion means anddepending therefrom for attaching an object to be recovered thereto;plate means disposed at predetermined positions on said buoyant chambermeans for facilitating the attachment of vacuum coupler means thereto,so as to effect the towing of said pontoon thereby;

ballast chamber means, having an opening therein, located within theinterior of said base portion means for containing ballast meanstherewithin;

weighted hatch means fitting the opening of said ballast chamber meansand releasably secured to said base portion means for providing closuremeans for said ballast chamber means;

ballast chain means stored within said ballast chamber means and securedto said weighted hatch means in such manner as to be jettisoned fromsaid ballast chamber means when said weighted hatch means is releasedfrom said base portion means; and

restraining means connected between said ballast chain means and saidbase portion means for limiting the movement of said pontoon in responseto the jettisoning of said ballast chain means.

2. A salvage pontoon according to claim 1 in which said buoyant chambermeans further comprises:

bulkhead means located within said buoyant chamber means and attachedthereto for the separation thereof into a plurality of watertightcompartments;

gas supply means located in at least one of said watertight compartmentsfor providing buoyant gas for said pontoon means;

standpipe means located in another of said watertight compartments fortransfer of water therethrough in such a manner as to flood or exhaustsaid buoyant chamber means; and

means connected between said gas supply means and said standpipeequipped water tight compartment for the selective transfer of gastherethrough in such a manner as to effect the expulsion or admission ofwater, so as to alter the buoyancy of said pontoon.

3. A salvage pontoon according to claim 2 in which said gas supply meanscomprises a cryogenic Dewar for containing therein gas in a liquidstate.

4. A salvage pontoon according to claim 2 in which said standpipe meanscomprises an open fluid conduit having an inverted U shape, with one endthereof in fluid communication with the exterior of said buoyant chambermeans, and with the other end thereof in close proximity with the lowerinterior surface of watertight compartment.

5. A salvage pontoon according to claim 2 in which means connectedbetween said gas supply means and said standpipe equipped watertightcompartment comprises a heat exchanger in thermal contact with theambient environment for transfer of the heat of vaporization of theliquified gas passing therethrough thereto.

6. A salvage pontoon according to claim 1 in which said restrainingmeans further comprises:

cable means attached to said ballast chain means at one end thereof andto the aforesaid base portion means at the other end thereof and woundinto a plurality of loops of predetermined lengths for providing aflexible tether between said anchor chain and said salvage pontoon;

cable sections extending across each of said loops to provide strainisolation therefor; and

remotely actuated cutter means disposed in cutting relation to saidcable sections for the selective severing thereof, so as to cause thecoil isolated thereby to unwind.

7. A salvage pontoon according to claim 1 in which said object engagingarm means further comprise in combination:

an elongated member attached to said base portion means in such manneras to extend a predetermined distance therefrom;

mounting plate means effectively attached to said elongated member forsurface contact with the object to be recovered; and

explosive stud means mounted on said mounting plate means and positionedso as to drive studs in said object for fastening said plate thereto insuch a manner as to effect a unitary structural connection therebetween.

8. A salvage pontoon according to claim 7 in which said elongated membercomprises a flexible belted chain means.

1. A salvage pontoon for use in recovering a large object from a greatocean depth comprising in combination: buoyant chamber means forproviding regulatable buoyancy for said pontoon; base portion meansattached to said buoyant chamber means for providing mutual supporttherebetween; object engaging arm means attached to said base portionmeans and depending therefrom for attaching an object to be recoveredthereto; plate means disposed at predetermined positions on said buoyantchamber means for facilitating the attachment of vacuum coupler meanstheretO, so as to effect the towing of said pontoon thereby; ballastchamber means, having an opening therein, located within the interior ofsaid base portion means for containing ballast means therewithin;weighted hatch means fitting the opening of said ballast chamber meansand releasably secured to said base portion means for providing closuremeans for said ballast chamber means; ballast chain means stored withinsaid ballast chamber means and secured to said weighted hatch means insuch manner as to be jettisoned from said ballast chamber means whensaid weighted hatch means is released from said base portion means; andrestraining means connected between said ballast chain means and saidbase portion means for limiting the movement of said pontoon in responseto the jettisoning of said ballast chain means.
 2. A salvage pontoonaccording to claim 1 in which said buoyant chamber means furthercomprises: bulkhead means located within said buoyant chamber means andattached thereto for the separation thereof into a plurality ofwatertight compartments; gas supply means located in at least one ofsaid watertight compartments for providing buoyant gas for said pontoonmeans; standpipe means located in another of said watertightcompartments for transfer of water therethrough in such a manner as toflood or exhaust said buoyant chamber means; and means connected betweensaid gas supply means and said standpipe equipped water tightcompartment for the selective transfer of gas therethrough in such amanner as to effect the expulsion or admission of water, so as to alterthe buoyancy of said pontoon.
 3. A salvage pontoon according to claim 2in which said gas supply means comprises a cryogenic Dewar forcontaining therein gas in a liquid state.
 4. A salvage pontoon accordingto claim 2 in which said standpipe means comprises an open fluid conduithaving an inverted ''''U'''' shape, with one end thereof in fluidcommunication with the exterior of said buoyant chamber means, and withthe other end thereof in close proximity with the lower interior surfaceof watertight compartment.
 5. A salvage pontoon according to claim 2 inwhich means connected between said gas supply means and said standpipeequipped watertight compartment comprises a heat exchanger in thermalcontact with the ambient environment for transfer of the heat ofvaporization of the liquified gas passing therethrough thereto.
 6. Asalvage pontoon according to claim 1 in which said restraining meansfurther comprises: cable means attached to said ballast chain means atone end thereof and to the aforesaid base portion means at the other endthereof and wound into a plurality of loops of predetermined lengths forproviding a flexible tether between said anchor chain and said salvagepontoon; cable sections extending across each of said loops to providestrain isolation therefor; and remotely actuated cutter means disposedin cutting relation to said cable sections for the selective severingthereof, so as to cause the coil isolated thereby to unwind.
 7. Asalvage pontoon according to claim 1 in which said object engaging armmeans further comprise in combination: an elongated member attached tosaid base portion means in such manner as to extend a predetermineddistance therefrom; mounting plate means effectively attached to saidelongated member for surface contact with the object to be recovered;and explosive stud means mounted on said mounting plate means andpositioned so as to drive studs in said object for fastening said platethereto in such a manner as to effect a unitary structural connectiontherebetween.
 8. A salvage pontoon according to claim 7 in which saidelongated member comprises a flexible belted chain means.
 9. A salvagepontoon according to claim 7 in which said elongated member is a rigidstructural member having a predetermined configuration which conforms ina complementary manner with the shape of The object to be raised.